Balsa vs. Plywood: What’s the Difference?

• Plywood

  Plywood is a material manufactured from thin layers or “plies” of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured boards which includes medium-density fibreboard (MDF) and particle board (chipboard).

  All plywoods bind resin and wood fibre sheets (cellulose cells are long, strong and thin) to form a composite material. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed in at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent across all directions. There is usually an odd number of plies, so that the sheet is balanced—this reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it has high stiffness perpendicular to the grain direction of the surface ply.

  Smaller, thinner, and lower quality plywoods may only have their plies (layers) arranged at right angles to each other. Some better-quality plywood products will by design have five plies in steps of 45 degrees (0, 45, 90, 135, and 180 degrees), giving strength in multiple axes.

  The word ply derives from the French verb plier, “to fold”, from the Latin verb plico, from the ancient Greek verb πλέκω.

• Balsa (noun)

  A large tree, ver=161201, native to tropical America, with wood that is very light in weight.

• Balsa (noun)

  The wood of this tree.

• Balsa (noun)

  A raft or float, used principally on the Pacific coast of South America.

• Plywood (noun)

  Construction material supplied in sheets, and made of three or more layers of wood veneer glued together, laid up with alternating layers having their grain perpendicular to each other.

  “After the hurricane there was a severe regional shortage of plywood, especially exterior plywood.”

• Plywood (noun)

  A specific grade or type of this construction material.

  “We stock exterior plywoods, interior plywoods, and furniture plywoods.”

• Plywood (verb)

  To fit or block up with plywood.

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